Current surgical apparatus and techniques permit operations on progressively smaller and more delicate structures. Microsurgery typically involves operating on a structure while viewing it through a microscope. It is routinely used to operate on all areas of the body. Applications have been found in such varied fields as ophthalmology, otology, peripheral vascular surgery, urology, obstetrics, gynecology, neurosurgery, reconstructive surgery, periodontics and endodontics.
Dramatic reconstructive efforts, such as transplanting tissues from one area of the body to rebuild another or replanting severed digits, have now become commonplace. Microsurgical procedures, once highly unreliable, are an irreplaceable part of the surgical field with successful and predictable results.
Stereoscopic images provide our minds with large amounts of information quickly and intuitively. Stereoscopic images are easier to comprehend, more natural to work with, and more dramatic to view than "flat" monocular images. Binocular or stereoscopic vision involves the recognition of spatial relationships among objects. This relationship, commonly referred to as "depth perception", is essential for performing fine manual exercises. Nowhere is this interplay between stereoscopic vision and motion more acutely illustrated than the fine motions magnified and guided with the microscope during the microsurgery.
Useful binocular microscopes have been available since the last century. Such microscopes have come to be used by surgeons who view the procedure through a pair of microscope eyepieces.
A stereoscopic television monitoring system was developed as early as 1985. Using two monitors and a special mirror box located directly in front of the eyes of the surgeon, assistant, or medical student, the stereoscopic image could only be seen by a limited number of observers. Sugita et al. "Stereoscopic television system for use with the operating microscope. Technical note. J. Neurosurg 62:610-611 (1985).
A stereo operating microscope is disclosed in Reinhardt et al. "Stereo-Microvision", Bildgebung 1993; 60:105-109. As shown in FIGS. 1 and 3, a small camera microscope is substituted for the usual operating microscope. The stereoscopic image appears on a single monitor suspended above the patient. The surgeon wears passive spectacles having slightly tinted, circularly polarized lenses.
A similar system is described in Kobayashi et al., "Three-dimensional videomonitor in microsurgery", Neurochicurgia 1993, 36:129-130 (New York). A Zeiss operation microscope is equipped with two CCD camera heads. Three-dimensional ("3D") images of the operation field are observed in a TV monitor through polarization glasses. The 3D images may also be observed in a special observation room or recorded on videotape.
A system employing a single HDTV cameras is shown in Okudera et al. "Three-dimensional Hi-Vision System for Microneurosurgical Documentation Based On Wide-Vision Telepresence System Using One Camera And One Monitor", Neurol. Med. Chir. 1993 33:719-721 (Tokyo).
The systems of the prior art suffer from a number of shortcomings. One major shortcoming is illustrated by considering the many surgical procedures involving more than one physician working in the same microscopic field view, but accessed from different directions. Typically, two physicians participate, one as an "operator" or attending surgeon, the other as an assistant. Prior art systems failed to provide correctly oriented images through the microscope eyepieces or on a single monitor for physicians at different locations. This is a major impediment to the performance of the surgical technique. In maximizing access and visibility for the attending surgeon, the assistant must accept whatever position and viewpoint is left available.
It is an object of the present invention to provide improved stereoscopic on-screen surgical microscope systems.
It is another object of the present invention to provide apparatus and methods for permitting surgery participants to approach a surgical site from different directions while viewing a stereoscopic image of the operating field correctly oriented for their point of view.
It is a further object of the present invention to provide apparatus for retrofitting existing conventional surgical microscopes to provide equivalent three-dimensional displays to multiple participants.
It is known in the prior art to employ eyepiece adapters to convert conventional surgical microscopes for stereoscopic television monitoring. These systems have the advantage of permitting use of familiar and tried surgical microscopes. However, these systems have a number of possible disadvantages. The eyepiece adapters may not provide adequate parfocal operation of the microscope; the surgeon must refocus at the extremes of magnification when zooming in and out. Such eyepiece adapters may have a different field of view or different effective magnification or different depth of focus, requiring retraining of surgical personal to accommodate such changes. With such eyepiece adapters, it is also difficult to maintain the necessary precise alignment between the two separate cameras mounted on separate eyepieces. The stereoscopic effect may be destroyed by either camera slipping along its optical axis, slipping laterally across its optical axis or rotating about its optical axis. Finally, such eyepiece adapters disable the eyepieces from conventional use.
Accordingly, it is an object of the present invention to provide a camera pod for retrofitting conventional surgical microscopes to provide a depth of field, magnification, parfocality field of view, and consistent optical alignment comparable to unmodified microscope.
It is a further object of the present invention to provide a camera pod which can either replace a binocular microscope eyepiece fixture with a quick-release (or quick-change) stereo-video fitting or be attached to a second port of the microscope's beam splitter.
These and other objects and features will become apparent from a reading of the following summary and detailed description of the drawings.